It is said that one of
Pythagoras' students discovered this proof. However, Pythagoras' entire world view was based on
natural numbers and their ratios, the
rational numbers. He believed that the universe was founded upon these, and so the concept of
irrational numbers was
heresy to him. He had the student murdered (
drowned, which was the usual form of
execution for
Pythagoreans who had broken the group's laws) to prevent the idea from spreading. Thus, the person who laid the foundation for western science also (in spirit) laid the foundation for
the dark ages,
religious intolerance and the
Inquisition.
Keep in mind that there are no direct written records of Pythagoras' life and work, and all information about him is indirect or conjecture, so this story may be untrue.